GJB2 and hereditary palmoplantar keratoderma: Differing mostly in various types of epidermal disorders, the syndromic HL associated with dominant GJB2 mutations includes keratitis-ichthyosis-deafness (KID, MIM148210) syndrome, hystrix-like ichthyosis with deafness (HID, MIM602540), palmoplantar keratoderma (PPK, MIM148350) with deafness, Vohwinkel syndrome (MIM124500) and Bart-Pumphrey syndrome (MIM149200).